Addition Of Excess Research Articles

Click Preparing UV‐Curable Polybutadiene Films With Good Thermal and Mechanical Performances by Using Multifunctional Mercaptan as a Cross‐Linking Agent

ABSTRACTUltraviolet (UV)‐curable maleic anhydride liquid polybutadiene films were prepared by using pentaerythritol tetra(3‐mercaptopropionate) (PETMP) as the crosslinker in 10 s. Fourier transform infrared (FTIR) spectra showed that maleic anhydride ring opened rapidly and reacted with sulfhydryl group to form thioester; meanwhile, SH group reacted with a double bond by thiol‐ene reaction, and both reactions resulted in the rapid increase in gel contents. Due to the unique flexible nature of maleic anhydride polybutadiene (MLPB) and the moderate cross‐linking degree provided by PETMP, the addition of PETMP in the range of 20%–25% significantly enhances their overall mechanical properties. The tensile strength of free‐standing MLPB‐PETMP films increased by three times, while its elongation reduced by less than 20%; their adhesion to carbon steel increased by more than three times to 5.0 MPa. Additionally, these films could be folded 180° on aluminum foil without damage and maintained a much lower wear level even after 3000 cycles of abrasion. However, the excessive addition of PETMP caused uneven distribution and aggregation, resulting in internal defects and thus the reduction in mechanical performances. Moreover, their thermal stability in air was also found improved, attributing to the increase in cross‐linking degree and the formation of higher strength SC bond.

Tidal-driven N2O emission is a stronger resister than CH4 to offset annual carbon sequestration in mangrove ecosystems.

The mangrove ecosystems store a significant amount of "blue carbon" to mitigate global climate change, but also serve as hotspots for greenhouse gases (GHGs: CO2, CH4 and N2O) production. The CH4 and N2O emissions offset mangrove carbon benefits, however, the extent of this effect remains inadequately quantified. By applying the 36h time-series observations and mapping cruises, here we investigated the spatial and temporal distribution of GHGs and their fluxes in Dongzhaigang (DZG) bay, the largest mangrove ecosystem in China, at tidal and monthly scales. The spatiotemporal variation of GHGs were mainly controlled by tidal-forced water mixing, outgassing and multiple biogeochemical processes. Tidal-driven porewater outwelling and sediment resuspension largely explained the excess addition of dissolved GHGs in tidal creeks. These lateral export combined with river input contribute significantly to surrounding water emission. Salinity controls CH4 emission in river-tidal creek-bay continuum, with concentration decreased by ∼100-fold from freshwater to seawater sites. N2O concentration was controlled by substrate supply for both nitrification and denitrification. Overall, the GHGs emissions in tidal creeks equal to 669-39,000 (7521±6401) g CO2-eq/m2/yr (CO2 contributed ∼88-91%) to atmosphere. In particular, CH4 and N2O contribute 8-366 (124±78) g CO2-eq/m2/yr and 59-2260 (712±525) g CO2-eq/m2/yr, together offsetting 8.7±2.1% of annual mangrove carbon sequestration, with a larger contribution from N2O (7.4%). Our findings highlight the importance of simultaneous quantification of non-CO2 GHGs to accurately assess blue carbon capacity.

The effect of the synthesis temperature and time on the formation of boron suboxide

Abstract Boron suboxide (B6O), offering a good balance between abundance of its constituents and promising tribological performance, is intriguing. Applications such as cutting tools, high-wear resistant coatings, and ballistics would benefit from such properties, however a feasible synthesis method is yet to be realized. The synthesis of B6O under atmospheric pressure is a challenging pursuit, and there is insufficient thermodynamic data for the formation of boron suboxide in the literature. In this study, boron suboxide powder was synthesized by reducing B2O3 by amorphous boron. Phase analysis of the formation of boron suboxide was demonstrated within the temperature range of 1200–1350 °C. The amorphous phase beside boron suboxide is present for all temperature treatments, but the best fitting crystalline phase was observed of the powder synthesized at 1300 °C. The powder was also heat treated at 1300 °C for various hours (2–6 h), and the crystalline phase was only observed for the powder heat treated for 4 h. The morphology of synthesized powder exhibited a star-like morphology. The production of B6O-TiB2 composite powder by reduction of TiO2 by amorphous boron with the excess addition of boron is also reported in this study.

Heterostructured Al2O3@BNNS/epoxy‐POSS/epoxy composites with excellent thermal conductivity, dielectric, and thermal properties

AbstractHigh thermal conductivity (λ) composite with excellent dielectric, mechanical, and thermal properties are critical to the reliability and safety of electrical devices. However, the excessive addition of thermal conductive fillers may lead to severe performance degradation. Heterogeneous structured alumina‐hexagonal boron nitride nanosheets (Al2O3@BNNS) fillers were prepared by electrostatic self‐assembly method. Owing to synergistic effect of spherical Al2O3 and sheet BN, and much low interface thermal resistance, λ of the epoxy resin with 20 wt% Al2O3@BNNS2 is raised to 0.84 W·m−1·K−1, 86.67% higher than that of Al2O3/BN/EP composite. Furthermore, epoxy‐based polyhedral oligomeric silsesquioxane (EP‐POSS) was incorporated to further optimize dielectric property of the composite. The λ of the composite is slightly decreased, but the dielectric constant and dielectric loss are reduced to 2.954 and 0.01058, respectively, due to the unique cage structure of EP‐POSS and excellent compatibility of EP‐POSS with the matrix. The composite also exhibits favorable mechanical properties with an impact strength of 86.2 MPa and a bending strength of 7.81 kJ·m−2, as well as outstanding thermal stability, suggesting its promising prospects for advanced electronic devices.Highlights fAl2O3 and fBNNS electrostatic self‐assemble into heterostructured fillers. The λ of Al2O3@BNNS2/EP composite is much higher than the others. The cage‐like EP‐POSS is used to improve dielectric properties of the epoxy resin. The ε and tanδ of composites at 1 MHz are only 2.954 and 0.01058, respectively.

Graphite-enhanced methanogenesis in coal measure shale anaerobic digestion: Implications for increasing gas yield and CO2 utilization

Anaerobic digestion (AD) of coal measure shale (CMS) for methane production is a promising technology for increasing yield of coal measure gas (CMG) wells. However, improving methane production efficiency of CMS remains a challenge. Conductive material has been shown to promote biogas production in different AD systems, but its effectiveness in CMS requires investigation. In this study, graphite was selected as conductive material due to its low cost and suitability for field applications, and its effects on methane production was investigated. The results indicate that as graphite concentration increases from 0 to 1.6 g/L, the methane production of CMS increases. However, when the graphite concentration reaches 2.0 g/L, the methanogenesis is inhibited, resulting in lower methane production compared to the control group. In the group with a graphite concentration of 1.6 g/L, the abundances of Romboutsia and Pseudomonas increase, which improves the compatibility of the microbial community with the CMS AD system and causes the amount of the substrates for methanogenesis to increase. Also, the direct interspecies electron transfer between Methanobacterium, Methanosaeta and Pseudomonas is strengthened, which enhances the methane production. However, excessive addition of graphite (2.0 g/L) intensifies the competitions from dissimilatory iron reduction and sulfate reduction reactions for substrates and electrons with the methanogenesis, causing the methane production to decrease. This study confirms the effectiveness of graphite in enhancing methane production of CMS, and the promoted hydrogenotrophic methanogenesis enhances the CO2 methanation, which offers an efficient pathway for increasing CMG well yield and enabling CO2 underground utilization.

Improvement of Mechanical Properties and Corrosion Resistance of As‐Extruded Mg–2Zn–2Al–0.3Mn Alloy Through Y Addition

The microstructure of as‐extruded Mg–2Zn–2Al–0.3Mn–xY (0 ≤ x ≤ 5 wt%) alloys are investigated, revealing the influence of grain size and second‐phase particle size on the mechanical properties and corrosion resistance of alloys. Additionally, the alloy composition is optimized. In the results, it is indicated that all alloys undergo complete dynamic recrystallization. The average dynamic recrystallization grain size decreases, accompanied by the appearance of Al2Y and (Al, Zn)11Y3 particles whose contents and sizes increase as Y content increases. Therefore, the mechanical properties improve due to fine grain strengthening and fine particle dispersion strengthening, while corrosion resistance benefits also from the grain refinement at Y contents between 0 and 3 wt%. A rapid increase in size and number of larger second‐phase particles leads to a decrease in the alloys’ mechanical properties corrosion resistance, with excess addition of Y. Accordingly, an optimized Y addition is determined to be 3 wt% in this study.

Enhancing oxygen‐blocking properties of HfB2‐MoSi2‐SiC coating by CeO2 modification

AbstractTo alleviate the destructive alteration of the glass layer surface caused by gas evolution during the oxygen‐blocking process of the HfB2‐MoSi2‐SiC coating, CeO2 was incorporated to modify HfB2‐MoSi2‐SiC coating, and the anti‐oxidation mechanism at 1700°C in air was investigated. Compared with the unmodified HfB2‐MoSi2‐SiC coating, the addition of the refractory CeO2 to the Hf‐B‐Si‐O system leads to the formation of a stable Hf‐Ce‐B‐Si‐O complex phase glass, which substantially enhances the viscosity, stability, and self‐healing sealing properties of the glass layer. The introduction of 0.75 vol.% CeO2 significantly lowers the oxidative activity of the HfB2‐MoSi2‐SiC coating, boosting its average protective efficiency to 99.96% and reducing the maximal oxygen permeability by 43.48%, thus exhibiting superior oxygen‐blocking performance. However, excessive addition of CeO2 leads to an overabundance of oxygen release through its distinctive oxygen vacancy mechanism, which accelerates the formation of Hf‐oxides, resulting in excessive viscosity on the coating surface and leaving oxidation defects unrepaired.

The Influence of Nickel Doping on the Metal-Oxide in Solution-Processed Transistors Based on Indium Zinc Oxide

Solution-processing of nickel zinc oxide (IZO) thin-film transistors (TFTs) is gaining traction as a cornerstone of future display technology, promising cost-effective production. However, achieving stability in the off-current state of IZO without using Ga, a less eco-friendly dopant, remains a challenge. This study proposes a solution-based doping method for IZO semiconductors employing a Ni carrier suppressor and examines the impact of Ni on transistor operation. By leveraging the similar size of Ni2+ to Zn2+, an optimal Ni concentration selectively substitutes Zn sites, leading to a reduction in hydroxide groups bonded to Zn and enhancing the bonding strength of Ni with O. Conversely, excessive Ni addition impedes the formation of a smooth thin film. Ni-doped IZO TFT devices with optimized Ni concentrations exhibit superior performance, characterized by significantly lower off-state currents while maintaining high on-state currents compared to conventional IZO TFTs. This approach expands the repertoire of solution-processed metal oxide semiconductors, offering a sustainable alternative for carrier suppression and facilitating the cost-effective and straightforward fabrication of TFTs.

Reaction of Calcium Titanate with Al Metal in Molten CaCl2

A new innovative production process of Ti production replacing the Kroll process is desired. The authors have been researching the production of Al-Ti alloy by Al reduction of TiO2 in molten CaCl2. It was shown in our previous study that Ti was reduced by the reaction of Al metal and CaTiO3 in molten CaCl2 at 1500°C, and that excess CaO addition was effective. However, the Ti content in the obtained Al-Ti alloy was still very small. In this study, the effect of Al-Ti alloy formation in molten CaCl2 containing Ca4Ti3O10 was investigated, and the appropriate condition for Al-Ti alloy formation was studied. Calcium titanate: Ca4Ti3O10 was prepared by sintering a molded mixture of CaO and TiO2, and a small Al lump was used as reductant. The influence de-greasing of the Al lump by NaOH solution as pretreat was examined in this study. Molten CaCl2 containing Ca4Ti3O10 with the Al lump was kept for 1~1.5 hour at 1400°C~1450°C, and cooled down. The Al lump after the experiment was rinsed with pure water, and analyzed by XRD and SEM-EDX. Figure 1 shows the dependence of Ti content in the Al lump on the immersion time. A small amount of Ti was detected in Al lump, and the Ti content varied with the immersion time. In the case that the Al lump without the pretreatment was used, the Ti content slightly increased with the immersion time, but the content was only 0.32 at% for 1.5 hour immersion at 1400°C. It was shown in our previous study that the Ti content was 0.06 at% in molten CaCl2 with CaTiO3, and that the content became 0.62 at% in the bath containing CaTiO3 with extra CaO where the molar ratio of CaO to TiO2 was 4:3. The result in this study is consistent with our previous study, which implies that the type of titanate ion in the bath strongly affects its chemical reduction by Al. The pretreatment of the Al lump strongly affected the Ti content; in the case that the Al lump with the pretreatment was used, the Ti content remarkably increased with the immersion time, and the content became 6.74 at% for 1.5 hour immersion. Since the Ti content did not reach a plateau even after 1.5 hour, a higher Ti content is expected by longer immersion. The Ti contents at 1400°C and 1450°C were almost the same, so the temperature dependence of this reaction seems not significant. Since the reaction seemed not to reach the equilibrium and the Ti content in Al was still insufficient, a further investigation should be necessary for the development of effective Ti production by this method. The researches on the influence of the titanate concentration and on the interface control other than de-greasing can lead more effective reaction. Figure 1

Growth of Solid Electrolyte Li1+X Al x Ti2-X (PO4)3 Single Crystals

The bulk single crystals are useful for our understanding of interfacial properties. Single crystals of lithium ion conductor, which can reveal intrinsic electrochemical properties, are an essential material for the development of high-performance all-solid-state lithium-ion secondary batteries. Li1+x Al x Ti2-x (PO4)3 (LATP) has a high ionic conductivity of ~10-3 S/cm at room temperature and show promise for the application of solid electrolyte for all solid-state batteries1, 2). We have tried to grow LATP crystals by floating zone method. Lithium phosphate such as Li4P2O7 evaporated from the molten zone during the crystal growth. As the result, AlPO4 and TiO2 phases precipitated in the LATP grown crystals. Therefore, excessive addition of lithium phosphate into the feeds to compensate for the evaporation component is necessary for LATP crystal growth. Next, we grew LATP crystals using the feed with a Li4P2O7 excess from the LATP composition by the melt slow cooling method. As the result, we have successfully grown LATP single crystals as shown in Fig 1, when the crystals were grown with a molar ratio of LATP : Li4P2O7 = 1 : 1, a maximum temperature of 1400°C, and a slow cooling rate of 5°C/h. The concentration of Al in the grown crystals was x = 0.16, which is approximately half of the feed concentration (x = 0.3). The crystal orientation was [100], and the ionic conductivity was σ[100] = 9.1 × 10-4 S/cm at room temperature.Reference1) H. Aono et al., J. Electrochem. Soc., 137, 4, 1023-1027 (1990).2) Yihzou Zhu et al., J. Mater. Chem. A 4, 3253 (2016). Figure 1

Oxygen Evolution Enhancement of Oxalate-Based Nickel-Iron MOF through Bipyridine Coordinated Strategy.

The catalytic performance of oxalate-based Ni-Fe metal-organic frameworks (MOFs) in the oxygen evolution reaction (OER) was investigated via a coordination strategy. The bidentate chelating ligand 2,2'-bpy (2,2'-bipyridine), was utilized to improve the catalytic kinetics under ambient conditions. The results revealed that a MOF-to-MOF transformation including the formation of [M(2,2'-bpy)n]2/3+ (M = Ni/Fe, n = 1-3) could boost alkaline OER, giving an impressive ultralow overpotential of 220 mV at a current density of 10 mA/cm2 in a 1 M KOH solution, surpassing the performance of control group activity of oxalate-based Ni-Fe MOF. However, excessive addition of the ligand had a negative effect, leading to decreased activity. Further investigation revealed the double role of 2,2'-bpy: Both promote and suppress catalytic reactions. The catalytic mechanism was then discussed, highlighting the potential of secondary ligands to effectively fine-tune the catalytic behavior of these materials.

Axial compressive and long-term shrinkage behaviors of self-compacting recycled concrete reinforced with recycled glass fiber

Self-compacting recycled concrete (SCC) has properties of significant shrinkage deformation and early cracking, which limits its wide application in civil engineering applications. Waste fiber addition offers an effective solution to these challenges. This research focuses on waste glass fiber and explored the impact of various parameters on the performance of recycled glass fiber-reinforced self-compacting recycled aggregate concrete (RGF-SCRC). Incorporating waste glass fiber effectively inhibits the long-term shrinkage rate of RGF-SCRC and improves its axial compressive strength, with the improvement of 2.2∼15.3 % in axial compressive strength and a reduction of 17.9∼66.5 % in the long-term shrinkage rate. However, excessive fiber addition shows an negatively effect on the performance of RGF-SCRC. The optimum addition was concluded as 7.5 kg/m³. On the other hand, the waste alkali-resistant glass fiber showed a higher improvement than waste glass fiber. Moreover, microstructure analysis reveals that the waste fibers could be uniformly dispersed within the investigated specimen, effectively bridging gaps and significantly enhancing the concrete’s strength and toughness. Furthermore, the number of large pores and overall porosity were reduced, resulting in greater compactness, improved axial compressive strength, and reduced long-term shrinkage of RGF-SCRC. After 180 days of curing, the porosity of the specimens significantly decreased when compared to the 28 day curing specimens. Based on experimental results, the axial compression stress-strain relationship and long-term shrinkage curves of RGF-SCRC were fitted and modified, and proposed an axial compression constitutive relationship and a long-term shrinkage theoretical analysis model which are applicable to RGF-SCRC. The models' correctness was verified by comparing them with experimental results. These research outcomes offer valuable insights for the future practical implementation of RGF-SCRC.

Effects of alloying elements on the corrosion behavior and discharge performance of Al-Zn-Mg-In-Ti-Sn sacrificial anode

A range of Al-Zn-Mg-In-Ti-Sn sacrificial anode alloys were designed and prepared, and the effects of In, Sn and Ti elements on the microstructure, self-corrosion and discharge properties of the alloys were investigated by orthogonal experiments. The experimental results indicate that In and Ti are solidly dissolved in the matrix, and Sn exists as Mg9Sn5 phases at the grain boundaries. Ti refines the grain size. The order of alloying elements affecting the corrosion rate and current efficiency of Al-Zn-Mg-In-Ti-Sn alloy is In>Sn>Ti. In promotes the activated dissolution of the anode due to dissolution-redeposition mechanism, but excessive addition of In inhibits the shedding of discharge products, leading to deteriorative discharge activation. Addition of Sn in Al anode increases the amount of anodic Mg9Sn5 phases and promotes the discharge activation of the substrate due to the galvanic corrosion. Al-5.5Zn-1.0Mg-0.02In-0.04Sn sacrificial anode has a current efficiency of 98.6 % and an actual capacity of 2816.9 Ah/kg, demonstrating an excellent discharge performance. During the discharge process, anodic dissolution mainly occurs along grain boundaries and the second phases, forming corrosion pits and then expanding over time. The accumulation of discharge products and excessive second phases leading to grain detachment significantly decrease the current efficiency of the Al-Zn-Mg-In-Ti-Sn alloy.

Highly porous Ni/MgO-ZrO2 catalysts for dry reforming of methane and the effects of MgO addition on the mechanisms

Dry reforming of methane (DRM) is a promising pathway to convert greenhouse gas into syngas. However, the commonly used Ni based catalysts suffer deactivation due to severe sintering and coking. In this paper, a series of porous Ni/MgO-ZrO2 catalysts (5Ni/xM(1-x)Z, x = 0, 20, 40, 60, 80 wt%, respectively) with high specific surface area were synthesized by a facile combustion method followed by incipient impregnation. It is found that the appropriate amount of MgO (40 %) addition in ZrO2 favors high porosity and high specific area. More MgO enhances the basicity of the catalyst as well as the metal-support interaction (MSI) by the formation of NiO-MgO solid solution, thus improving DRM activity and coking resistance. However, excessive MgO addition leads to over-strong MSI and lower porosity, resulting in lower DRM activity. The catalyst with 40 % MgO addition (5Ni/40M60Z) exhibits the best activity (conversions of CH4 ∼ 76 %, CO2 ∼ 83 %) and stability (>50 h) at high GHSV = 96000 ml/gcat·h and 750 °C. in situ DRIFTS reveals the mechanism that MgO addition improves DRM activity and stability. Compared with ZrO2 where CO2 adsorbs as monodentate carbonate, CO2 tends to adsorb on 40 %MgO-60 %ZrO2 as bidentate carbonate and then easily transfer to more stable intermediate bidentate formate, thus improving DRM activity and coking resistance. This study provides new insights on the role of Mg addition in Ni/MgO-ZrO2 DRM catalysts.

Effect of Co content on microstructure and properties of TiCN-TiB2 cermets prepared by spark plasma sintering from a TiCN-B4C-Ti-Co system

Series of TiCN-TiB2 cermets were in situ prepared from the TiCN-B4C-Ti-Co system via spark plasma sintering (SPS). The effects of Co content on the densification, microstructure, mechanical properties, and wear resistance of TiCN-TiB2 cermets were investigated. The results showed that the Co addition had little effect on the phase composition of the sintered cermets, but had significant influences on the densification, microstructure and mechanical properties. Appropriate addition of metal Co could enhance densification and promote the grain growth of ceramic phases, but excessive addition resulted in a decrease in hardness and wear resistance. When the Co content was 10 wt%, the cermet obtained the optimal comprehensive performance (a hardness of 1757 HV and a fracture toughness of 7.02 MPa•m1/2). Meanwhile, the cermets with 10 wt% Co addition exhibited optimum wear resistance properties due to a good combination of hardness and toughness and moderate grain size. In addition, the formation process and strengthening mechanism in present system were discussed in detail. Results from this work could provide valuable references for the fabrication of TiB2 reinforced TiCN-based cermets.

Influence of calcium-doped on the conductivity of NASICON-type Na3Zr2Si2PO4 solid electrolyte

Sodium-ion solid electrolyte has many advantages such as high safety, good ionic conductivity, and strong chemical stability. NASICON-type Na3Zr2Si2PO4 solid electrolyte was prepared by high-temperature Solid State Reaction (SSR). X-ray Diffraction (XRD) show that the 20 % excess addition of Na and P elements will reduce the formation of ZrO2 impurity phase and increase the ionic conductivity to 1.01 × 10−4 S cm−1. On the basis of this experiment, Ca was added to dope the Na site in Na3Zr2Si2PO4 with different contents. Electrochemical impedance spectroscopy (EIS) results show that the conductivity of Ca2+ doped Na2.7Ca0.15Zr2Si2PO4 is significantly increased to 1.53 × 10−4 S cm−1, the electronic conductivity is 3.99 × 10−8 S cm−1, and the activation energy is 0.32 eV. Cyclic voltammetry testing demonstrated stable chemical properties below to 5 V. Na | Na2.7Ca0.15Zr2Si2PO4 | Na3V2(PO4)3 battery still maintains a high capacity retention rate of 98.76 % after 200 cycles at 25oC-0.2C. It indicating that the new 0.15molCa-doped Na2.7Ca0.15Zr2Si2PO4 has the highest electrical conductivity, which provides a new research idea for sodium-ion solid-state batteries and has great potential in solid-state battery applications.

Thiol‐Ene Coupling Reaction for Functionalization of Non‐Activated Alkenes: An Experimental Study on the Chemistry of the Methyl Oleate Amination

AbstractThis work investigates the functionalization of molecules with non‐activated internal double bonds via thiol‐ene coupling (TEC) reaction. A comprehensive study of the reaction between cysteamine hydrochloride (CAHC) and methyl oleate (MO) was carried out. A series of reactions were conducted under different operating conditions in order to assess their effect on conversion and selectivity. Different conditions were considered like the type of atmospheres and solvents, a portionwise addition of CAHC, reagents concentrations, and excess of CAHC. Maximum conversion and selectivity were reached under inert atmosphere, diluted conditions, ethanol as solvent, and the addition of CAHC at the beginning of the reaction with a molar ratio of CAHC/MO of 3/1. This provides an approach for analyzing more complex reaction systems.

Protein Engineering of Nicotinamide Riboside Kinase Based on a Combinatorial Semirational Design Strategy for Efficient Biocatalytic Synthesis of Nicotinamide Mononucleotides.

Industrial biosynthesis of β-nicotinamide mononucleotide (β-NMN) lacks a highly active nicotinamide riboside kinase for the phosphorylation process. Cumbersome preprocessing steps and excessive ATP addition contribute to its increased cost. To tackle these challenges, a docking combination simulation (DCS) semirational mutagenesis strategy was designed in this study, combining various modification strategies to obtain a mutant NRK-TRA with 2.9-fold higher enzyme activity. Molecular dynamics simulations and structural analysis demonstrate the enhancement of its structural stability. High-density fermentation was achieved through a 5 L fermentation tank, with a titer reaching 208.3 U/mL, the highest in the current report. An ATP-cycling whole-cell catalytic system was employed and optimized by introducing a polyphosphate kinase 2 (PPK2) recombinant strain, and 15.16 g/L β-NMN was obtained through a series of batch transformation experiments. This study provides a new strategy for the efficient screening of highly active enzyme variants and offers a green and promising biotransformation system for NMN production.

Wear, corrosion and cavitation erosion behavior of WC-reinforced FeCrNiMnAl ceramic-high entropy alloy composite coatings by laser cladding

FeCrNiMnAl/WC ceramic-high entropy alloy (HEA) composite coatings with various WC content are prepared on 304 stainless steel (304 SS) by laser cladding (LC). Experimental results show that residual tensile stress of coatings increases with the addition of WC content, and excessive addition of WC leads to cracking in 15WC and 20WC. All coatings are composed of BCC and WC duplex, and the addition of WC particles significantly refines grain size of the coatings. Compared with FeCrNiMnAl HEA coating, the coatings with WC addition exhibit improving mechanical properties and wear resistance due to the combined effect of multiple strengthening mechanisms. Among the tested coatings, 10WC exhibits the highest cavitation erosion (CE) resistance due to its excellent mechanical properties and corrosion resistance.

The efficient metal- and halogen-free polymer catalyst for the intensification on CO2 cycloaddition

An environmentally friendly polymer catalyst (PAS) was synthesized via inverse emulsion polymerization using acrylic acid (AA) and 1-vinyl imidazole (VI) as monomers. The excellent catalytic activity of PAS was attributed to the synergistic effects of the carboxyl groups (-COOH) as hydrogen bond donors and N-heterocyclic carbene (NHCs) as electron donor, as well as the swelling properties of the polymer, which can enrich the substrate into the polymer network, increasing the contact between the substrate and active sites. Characterization results from thermogravimetric (TG) analysis and small-angle X-ray scattering (SAXS) showed that the excessive imidazole addition disrupted the polymer's chain-like structure, significantly reducing its swelling properties. And, the catalytic performance is influenced by both the amount of imidazole in PAS and the swelling properties of the polymer. Finally, the reaction mechanism of the CO2 cycloaddition reaction catalyzed by PAS was proposed and validated through density functional theory (DFT) calculations.